C57B1/6 mice were passively immunized with antibodies to 2,3,7-trichlorodibenzo-p-dioxin (TriCl-DD) one day prior or one day following treatment with 250 mg/kg (LD50-30) of 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) in an attempt to explore the protective capabilities of passive immunization against dioxin exposure. Statistical analysis of body weight loss and mortality indicated no protective effect of passive immunization to TCDD exposure.